Respiratory mucous glycoproteins (MGP) are produced by at least three cell types in the respiratory tract. These glycoproteins are relatively heterogenous in size; however, no specific characteristics are available for MGP secreted by different cells. Therefore, quantitation of MGP secreted by different cells has not been possible. Current work is directed toward the development of murine monoclonal antibodies that recognize specific secretory products of human submucosal gland mucus and serous cells and human epithelial goblet cells. To date, seven antibodies have been produced. Each has affinity for secretory products of goblet cells, submucosal gland mucus cells or both. Such antibodies have allowed for the development of ELISA assays for specific secretory products and for the separation by affinity chromatography of MGP of a specific cell of origin. ELISA assays are now in use in the laboratory to quantitate secretory cell product release in response to a variety of receptor mediated stimuli. This has resulted in the definition of mascrinic receptor subtype involved in cholinergic stimulated airway secretion and in the identification of peptides which stimulate human submucosal gland secretion. Further these techniques will be used to measure secretion produced in vivo. Studies are underway to quantitate airway mucin secretion in bronchoalveolar lavage fluid of patients with airway inflammation.